This invention relates generally to a control device for use in connection with machines for continuous winding of webs of material preferably a foil of synthetic material on a succession of reels. More particularly, this invention relates to a device for severing a continuously fed web from one reel and applying the disconnected end portion of the web to a new reel. This severing and laying-on device is applicable in turn-over type winding machines where a plurality of reels is supported for movement on a circular path and the web is guided past a contact roller pressing against the roll of the web being wound on a first reel; as soon as the windings on the first reel attain a desired diameter, and a new second reel has been moved opposite the contact roller, the latter in cooperation with an auxiliary guiding roller is displaced toward the circular path and in doing so the two rollers stretch the web around the major part of the periphery of the new second reel and the web is discontinued by the aid of a severing element that is supported for movement between the auxiliary guiding roller and the new reel
In winding webs of materials such as plastic foils especially very thin and flexible plastic foils, where very high feeding speeds are involved, every increasing requirements are put on the manner how a leading portion of the web is applied to a new empty reel. Especially it is required that the newly laid-on portion of the web be free of folds since any irregularities at the beginning of the web formed of a very thin plastic foil reproduce themselves during the winding of the whole roll and may impair the quality of the foil. To avoid this drawback, a control device cooperating with the winding machine has been described and published in the German Pat. No. 2,232,338. In this prior art device a contact roller is urged against the windings of the web or against the empty reel. Due to the fact that the roller is stationarily arranged on the swing arm, it follows passively the increasing diameter of the wound web roll. In the course of the severing and laying-on process, an auxiliary guiding roller holds a winding of the advancing web portion on the empty reel so that a certain circumferential section of the empty reel is covered by the advancing web. In order to achieve a fold-free application of the new web on the empty reel, the known device has a severing element that is supported for swingable movement about the axis of the empty reel and has a surface extending concentrically with respect to the reel. A pressure air outlet is directed against the web of material and the whole structure has a form of an air box. During the severing and laying-on process the severing element together with its support moves against the web section between the auxiliary guiding roller and the reel, severs the web and introduces a new leading section of the web on the periphery of the empty reel as far as to the intake split or gap between the contact roller and the reel whereupon the lay-on process is finished. Due to the relatively small looping angle of the advancing web on the empty reel prior to the severing operation the new leading portion of the web has to travel a considerably long distance on the periphery of the reel before it reaches the intake gap between the contact roller and the reel. It is true that the prior art device by means of the above described construction of the support of the severing tool makes it possible even at high feeding speeds to attain a fold free application of the new starting section of the web. Nevertheless the disadvantage of this design resides in the necessity of additional bearings, additional drive and special construction of the support for the severing element so that considerable construction costs and operational and controlling expenditures result.
Accordingly, the primary object of this invention is to avoid the above-described disadvantages of prior art devices of this type. More particularly, an object of this invention is to provide a device which makes it possible to introduce the leading end of the web on the empty reel without forming any fold.
Another object of this invention is to provide a control device that is simple in structure and operation.
Still another object of this invention is to simplify the introduction of the web on a new reel. Furthermore, an object of this invention is to provide a device that makes it possible to increase feeding speed of the web.